Optical recording medium, and method for initializing the optical recording medium

Abstract

An optical recording medium including a transparent substrate; and at least one multi-layer information layer located on the transparent substrate and including a phase change recording layer configured to record information by changing its phase between a crystallization state and an amorphous state, a protective layer, and a reflection layer, wherein the average of partial response signal-to-noise ratio (PRSNR) in all data regions of the recording medium is not less than 15.0 after one direct overwriting (DOW1) cycle and the standard deviation of inter-track distribution of PRSNR is not greater than 0.3.

Description

TECHNICAL FIELD[0001]The present disclosure relates to an optical recording medium, and more particularly to a rewritable phase change optical recording medium which performing recording and reproduction using a blue laser. In addition, the present disclosure also relates to a method for initializing the optical recording medium.DISCUSSION OF THE BACKGROUND[0002]Recently, with increase in volume of information, a need exists for a recording medium, in which a large amount of information can be recorded at a high speed and a high density and the information can be accurately reproduced. Phase change optical recording media which perform recording and reproduction using a light beam, particularly, phase change optical discs, are media which have high access rate and which have such advantages as to have good signal properties, and to be able to perform high density recording and one-beam overwriting.[0003]Such phase change optical discs typically have a structure such that at least a ...

AI Technical Summary

Benefits of technology

The present patent provides an optical recording medium with a transparent substrate and at least one multi-layer information recording layer. The data regions of the medium have a high signal-to-noise ratio and the inter-track distribution of the ratio is uniform. The substrate has a wobbling groove with specific dimensions. The medium is initialized by a method that involves irradiating it with a laser beam and rotating it at a certain speed. The technical effects of this patent include improved recording quality and performance of the optical recording medium.

Problems solved by technology

When a laser beam having an erasure power irradiates a portion of the recording layer, the portion achieves a crystalline state independently of the previous state of the portion, resulting in erasure of information.

The recording layer in the as-depo. state typically has a low reflectance and therefore auto focusing operations or tracking operations performed by a driving system for CDs or DVDs become unstable.

However, with increase in record density of optical recording media, an initial recording property deterioration problem in that the initial recording properties of a recording medium deteriorate after several recording operations easily occurs.

In addition, an uneven initialization problem occurs in that when a medium is initialized by a conventional method (mentioned below), the properties vary in the medium depending on the properties of the light source used for the initialization, and thereby the properties of recorded portions greatly vary.

Specifically, the problem is that the recording medium has a low erasure rate after two recording operations (hereinafter referred to as “one direct overwriting” or “DOW1”) to ten recording operations, and the medium can have good erasure rate after about ten or more direct overwriting cycles.

The uneven initialization causes variation of recording properties of the recording medium.

As a result, it becomes difficult for the recording medium to have good recording properties in all the data regions of the recording medium.

Thus, the uneven initialization largely varies the recording properties of the recording medium.

However, it takes a long time to perform such an initialization operation, resulting in deterioration of productivity.

In addition, as mentioned above, the recording layer in the as-depo. state has a low reflectance and therefore auto focusing operations or tracking operations performed by a driving system for CDs or DVDs become unstable, thereby causing defective initialization.

However, an initialization method by which optical recording mediums can be initialized so as to have good properties in all the data regions has not yet been developed.

Therefore, an optical recording medium having even properties in all the data regions has not yet been obtained.

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